1. Field of the Invention
The present invention relates to a sheet feeding device for the automatic feed of individual sheets from a stack of sheets to an apparatus, the device comprising lower carrier rollers and upper feed rollers which resiliently rest against the lower carrier rollers.
2. Description of the Prior Art
Various conveying systems have been proposed for transporting an original through the treating stations of copying and reproduction machines. Thus, German Offenlegungsschrift No. 2,026,063 discloses, as part of a copying machine, a drum provided with a number of grippers arranged on and protruding from the drum suface, by which the leading edge of the original to be reproduced is clamped down.
German Offenlegungsschrift No. 2,365,228 discloses a gripping device comprising a clamping bar provided with a number of gripper fingers. The clamping bar is arranged within a drum, in a radially extending slot, and is pressed against a clamping surface in the interior of the drum by means of a system of levers actuated by an electromagnet with an armature, in order to clamp the original inserted into the slot.
The gripping device disclosed in German Offenlegungsschrift No. 2,343,133 is mounted on a revolving endless conveying system, for example two chains, and comprises a metallic gripping frame attached to the conveyor chains, movable metallic gripping jaws, and buffer cushions which prevent the photoconductive drum from being scratched or otherwise damaged by the approaching gripping device.
From German Auslegeschrift No. 1,902,112, a feeding device for copying machines is known in which the original to be copied is separated from a stack and transported, by conveyor belts, to the supporting table of an exposure station and is then deposited, also by conveyor belts, on a delivery stack. For this purpose, a first, switchable conveying system seizes the separated original and conveys it to the supporting table by means of a reversible conveyor belt driven by a reversible drive means.
The above-mentioned conveying systems comprise, as a common feature, a copy drum provided with individually integrated gripping fingers or with a rigid gripping bar extending over the surface of the drum, said fingers or said bar serving to grip the leading edge of the original being transported during rotation of the copy drum; alternatively, the original is transported by means of conveyor belts.
The above-mentioned known feeding systems are fixed components of a copying or reproduction apparatus and, by their structure and function, are unsuitable for feeding originals from the outside to the feed point of an apparatus in which the originals are to be processed.